The present invention relates to an implant for a device for osteosynthesis, in particular of the spine, of the type comprising a part intended for osseous anchoring and a body for fixation on a rod, in which the body presents a channel opening out at a rear part of the body, delimiting two lateral branches and open on each side of the body so as to be able to receive the rod. This implant also comprises a threaded plug adapted so as to be able to be screwed in a tapping formed in the inside walls of the two lateral branches in order to lock the rod in translation and in rotation.
Such an implant is described in French Patent Application 88/08,538 (Publication No. 2,633,177) filed on Jun. 24th, 1988 by the Applicant. This device, which permits fixation of a knurled rod to a vertebra, has certain disadvantages:
on the one hand, there is some difficulty in moving the rod after positioning of the threaded plug for fixation, and
on the other hand, the branches of the U-shaped body may undergo a certain spacing apart during tightening of the plug on the rod.